Imaging of frontal sinus disease: concepts, interpretation, and technology

ICAR: endoscopic skull-base surgery

BACKGROUND

Endoscopic skull-base surgery (ESBS) is employed in the management of diverse skull-base pathologies. Paralleling the increased utilization of ESBS, the literature in this field has expanded rapidly. However, the rarity of these diseases, the inherent challenges of surgical studies, and the continued learning curve in ESBS have resulted in significant variability in the quality of the literature. To consolidate and critically appraise the available literature, experts in skull-base surgery have produced the International Consensus Statement on Endoscopic Skull-Base Surgery (ICAR:ESBS).

METHODS

Using previously described methodology, topics spanning the breadth of ESBS were identified and assigned a literature review, evidence-based review or evidence-based review with recommendations format. Subsequently, each topic was written and then reviewed by skull-base surgeons in both neurosurgery and otolaryngology. Following this iterative review process, the ICAR:ESBS document was synthesized and reviewed by all authors for consensus.

RESULTS

The ICAR:ESBS document addresses the role of ESBS in primary cerebrospinal fluid (CSF) rhinorrhea, intradural tumors, benign skull-base and orbital pathology, sinonasal malignancies, and clival lesions. Additionally, specific challenges in ESBS including endoscopic reconstruction and complication management were evaluated.

CONCLUSION

A critical review of the literature in ESBS demonstrates at least the equivalency of ESBS with alternative approaches in pathologies such as CSF rhinorrhea and pituitary adenoma as well as improved reconstructive techniques in reducing CSF leaks. Evidence-based recommendations are limited in other pathologies and these significant knowledge gaps call upon the skull-base community to embrace these opportunities and collaboratively address these shortcomings.

Two huge maxillofacial osteoma cases evaluated by computed tomography

Osteomas are benign osteogenic neoplasms or hamartomas with a very slow growth rate. Osteoma is the most common mesenchymal neoplasm of the paranasal sinuses. In the jaws, the mandible is more commonly involved than the maxilla. Osteomas may occur at any age, but most frequently are found in individuals older than 40 years. Although most osteomas are small, some may become large enough to cause severe damage, especially those that develop in the frontoethmoid region. Osteomas composed solely of compact bone are uniformly radiopaque and those containing cancellous bone show evidence of internal trabecular structure. To determine and evaluate the exact extension and internal structure of these lesions, computed tomography (CT) is a more useful imaging modality in comparison to conventional radiography. Hereby, we discuss clinical and imaging features of two osteomas (one in the ethmoid sinus and the other in the mandible) along with the main differential diagnoses and pathologic features.

Isolated fungus ball mimicking mucocele or frontal sinus tumour: a diagnostic pitfall

Objective:

To demonstrate the clinical, radiological and diagnostic pitfalls of managing an isolated frontal sinus fungus ball, and to compare with the literature.

Material and methods:

Retrospective analysis of two cases and literature review.

Results:

Isolated frontal sinus fungus ball is a rare cause of frontal sinus disease. We present two cases of isolated frontal sinus fungus ball which pre-operatively were suspected to be either a tumour or a mucocele. In both cases, cheesy, clay-like material was found intra-operatively within the frontal sinus, suggesting a fungus ball. Effective treatment included surgical debridement via an exclusively endoscopic or an external approach, variously. Final histopathological and mycological analysis revealed Aspergillus fumigatus. A literature review revealed 20 reported cases of isolated frontal sinus fungus ball, confirming the low prevalence of the disease.

Conclusions:

Frontal sinus fungus ball should be considered in the differential diagnosis of chronic, nonspecific forehead symptoms. To evaluate the underlying disease, computed tomography scans should first be performed, followed by magnetic resonance imaging if malignancy is suspected. It is essential to be aware of the possibility of an atypical fungus ball appearance on computed tomography and magnetic resonance imaging scans. If bony destruction and calcification coexist on radiological images, then endoscopic biopsy is an indispensable part of the diagnostic procedure, and should be performed to collect material for both histological and mycological analysis, and to aid surgical planning. In cases of sinus fungus ball, an endoscopic approach for biopsy may be curative.

Paranasal sinus imaging

Endonasal surgery is currently extending its application beyond inflammatory sinonasal lesions to successfully treat both benign and malignant neoplasms. This progression has been possible by the detailed information provided by imaging techniques (CT, MRI and PET). Inflammatory diseases are the "domain" of CT. CT provides excellent details about the thin bony sinonasal walls separating the ethmoid from the anterior skull base and the orbit. Benign and malignant neoplasms are the "domain" of MRI because the tumor is more easily separated from adjacent structures, the periosteal linings (periorbita, dura mater) and perineural spread can be accurately shown. Whereas MRI precisely assess pre-treatment tumor extent, early submucosal local recurrences are difficult to demonstrate because of post-treatment changes of the anatomy and of the signal of treated tissues. Though diffusion-weighted imaging and dynamic contrast-enhanced techniques are promising developments, PET-CT may overcome the limits of morphological MRI.

Advances in imaging of the paranasal sinuses

Imaging technology has played a significant role in the diagnosis and management of sinonasal disorders. Plain sinus films are almost exclusively replaced by CT in the work-up for inflammatory sinus disease. MRI provides complementary information to CT in cases of sinonasal and skull-base neoplasms. The evolution of endoscopic surgical techniques for the paranasal sinuses and skull base is made possible by the parallel advancement of imaging technologies. Recent advances that are currently in clinical use have included multidetector row CT scanners and computer image-guidance systems for surgery. Three-dimensional CT angiography, image-guided CT-MR fusion, and intraoperative image-guidance are new techniques that are currently being evaluated. As imaging technology continues to advance, so does the capability to treat diseases beyond the sinuses and skull base with minimally invasive, endoscopic approaches.

Delayed post-traumatic frontal sinus mucopyocoele presenting with meningitis

PURPOSE

To highlight a rare but potentially serious complication of frontal sinus injuries.

PATIENT

A case of delayed post-traumatic frontal sinus mucopyocoele presenting with meningitis in a 23-year-old male patient is reported.

DISCUSSION

The anatomy of the frontal sinus is described in relation to the pathogenesis of muco(pyo)coele formation and the relevant literature is reviewed.

CONCLUSION

This case, in our opinion, emphasizes the importance of thorough evaluation and adequate management of craniofacial trauma involving the paranasal sinuses, with special regard to paediatric patients. Mucocoeles and mucopyocoeles are rare complications that can develop many years after trauma, thus necessitating a virtually life-long follow-up.

Post-trauma mucocele formation in the frontal sinus; a rationale of follow-up

The aim of the investigation was the evaluation of the follow-up for mucocele formation as a complication of frontal sinus fractures. A review of the literature was performed which showed only 10 adequately documented cases of mucocele formation after trauma. In our hospital between June 2001 and July 2002 three patients were treated for mucocele as a late complication following trauma to the frontal sinus. Our patients presented themselves with a mucocele, respectively 13, 22 and 35 years after the initial trauma. From this a suggestion is done for the follow-up of post-trauma patients. Mucocele formation is a complication, which can develop years after trauma to the frontal sinus. Treatment of these forms of mucocele is multidisciplinary. The review of the literature in combination with our own data showed no peak incidence of mucocele formation after trauma. We therefore advocate following the at-risk-patients for life, and to properly inform them about the possible development and symptoms, like swelling, diplopia, etc., of a mucocele.

Imaging of neoplasms of the paranasal sinuses

The assessment of sinonasal malignancies requires a multidisciplinary team approach.Advances in pretherapeutic imaging have significantly contributed to the managementof sinonasal tumors. CT and MR imaging play complementary roles in the assess-mentand staging of these malignancies by determining the presence or absence of exten-sionof disease into the skull base and its foramina, the orbit, and the intracranial compartment.

Imaging of neoplasms of the paranasal sinuses

The assessment of sinonasal malignancies requires a multidisciplinary team approach. Advances in pretherapeutic imaging have significantly contributed to the management of sinonasal tumors. CT and MR imaging play complementary roles in the assessment and staging of these malignancies by determining the presence or absence of extension of disease into the skull base and its foramina, the orbit, and the intracranial compartment.